1. Field of the Invention
The present invention relates generally to covers for liquid-retaining structures, covering systems that utilize such covers, and venting methods.
2. Description of Related Art
Covers for liquid-retaining structures, such as lagoons, ponds, basins, and tanks, have existed for many years. Such liquid-retaining structures have been used in a variety of environments, including holding fresh water or wastewater for industrial, municipal, and/or agricultural operations, and the like. Covers have been used to address issues such as odors, algae growth, heat loss, and gas production and collection associated with the retained liquids. Such gases include, for example, methane and hydrogen sulfide. Examples of such covers include those found in U.S. Pat. Nos. 3,991,900, 4,438,863, 5,265,976, 6,136,194, 4,294,589, 5,400,549, and 5,562,759.
Despite their utility in certain areas, current covers do not offer a simple, inexpensive way to address issues such as odor control or algae control while providing the ability to release gas at the same time. While certain of the covers identified above, such as those depicted in U.S. Pat. Nos. 5,400,549 and 5,562,759 (the disclosures of both of which are incorporated herein by reference) provide for a modular construction, the disclosed modules include large, insulative enclosures that span nearly the entire space of the module. As a result, the modules are expensive. Additionally, while gaps exist between the connected modules through which gas may escape, the covers lack a controlled gas-release system that does not depend upon modules being connected to each other. Of the non-modular covers that exist, some employ expensive, complicated systems of gas control that include pipes for directing the gas and pumps to stimulate the movement of the gas.